From owner-freebsd-net  Thu May 10  9:37:45 2001
Delivered-To: freebsd-net@freebsd.org
Received: from khavrinen.lcs.mit.edu (khavrinen.lcs.mit.edu [18.24.4.193])
	by hub.freebsd.org (Postfix) with ESMTP id 55BA637B424
	for <net@FreeBSD.ORG>; Thu, 10 May 2001 09:37:42 -0700 (PDT)
	(envelope-from wollman@khavrinen.lcs.mit.edu)
Received: (from wollman@localhost)
	by khavrinen.lcs.mit.edu (8.9.3/8.9.3) id MAA81740;
	Thu, 10 May 2001 12:37:39 -0400 (EDT)
	(envelope-from wollman)
Date: Thu, 10 May 2001 12:37:39 -0400 (EDT)
From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Message-Id: <200105101637.MAA81740@khavrinen.lcs.mit.edu>
To: Alfred Perlstein <bright@wintelcom.net>
Cc: net@FreeBSD.ORG
Subject: Re: getaddrinfo irritation
In-Reply-To: <20010510092401.M18676@fw.wintelcom.net>
References: <20010510082025.J18676@fw.wintelcom.net>
	<200105101540.LAA81367@khavrinen.lcs.mit.edu>
	<20010510090322.K18676@fw.wintelcom.net>
	<20010510090907.L18676@fw.wintelcom.net>
	<200105101612.MAA81594@khavrinen.lcs.mit.edu>
	<20010510092401.M18676@fw.wintelcom.net>
Sender: owner-freebsd-net@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org

<<On Thu, 10 May 2001 09:24:01 -0700, Alfred Perlstein <bright@wintelcom.net> said:

> I guess this is a no-no then?  It tries to match the protocol with
> the socktype.

Well, the specification appears to leave this possibility open.  It
says:

# A value of zero for ai_socktype means that the caller shall accept
# any socket type.

So it is not illegitimate for the library to say ``OK, he wants
protocol 6, so let's pick a socket type that we know has a protocol
6''; the application has already indicated that it doesn't care.

However, I would argue that any application that thinks it doesn't
care is broken.  So much of the API depends on whether the application
is using a connection-oriented or connectionless model that it is
difficult to conceive of any non-trivial application that didn't care
what sort of socket type it received.

So, I would suggest that the correct solution for your program is
instead:

	if (strcmp(protocol, "tcp") == 0)
		hint.ai_socktype = SOCK_STREAM;
	else
		hint.ai_socktype = SOCK_DGRAM;

...or even better, require the user to specify which model it was
using.  (Again, most programs only make sense for one or the other.)

-GAWollman


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-net" in the body of the message